Applying Automation and High-Throughput MALDI Mass Spectrometry for Peptide Metabolic Stability Screening

The discovery of peptide therapeutics represents a fast-growingsegment of pharmaceutical research. During the early discovery process,a large number of peptide candidates needs to be rapidly screenedfor metabolic stability in relevant biological matrices. In most cases,peptide stability assays are quantified using LC-MS/MS, whichmay take hours to analyze 384 samples and generates liters of solventwaste. Herein, we introduce a high-throughput screening (HTS) platformfor peptide stability assessment founded on Matrix Assisted LaserDesorption/Ionization (MALDI) mass spectrometry (MS). Full automationhas been implemented for sample preparation with minimal manual intervention.The limit of detection, linearity, and reproducibility of the platformwere evaluated, and metabolic stabilities have been determined fora number of peptide candidates. The MALDI-MS-based HTS workflow isable to analyze 384 samples in less than 1 h while only using 115 mu L of total solvent. Although this process allows for very rapidassessment of peptide stability, given the nature of the MALDI process,it is noteworthy that spot-to-spot variations and ionization biasare observed. Therefore, LC-MS/MS may still be needed for confident,quantitative measurements and/or when the ionization efficiency ofcertain peptides is inadequate using MALDI.